Multi-Zone Radiant Heating System - Williamson-Thermoflo GWC-070 Manual

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Install water piping

Multi-zone radiant heating system

Multi-zone systems require automatic regulation of the system sup-
ply temperature because of widely varying load conditions. Figure 23
(zone-valve zoning) and Figure 24 (circulator zoning) show suggested
piping for these systems.
Provide an automatic temperature control valve or
motor-operated valve which can be adjusted for the
desired supply water temperature. This is required to
protect the radiant system from excessive temperature.
Zone-valve zoning — The suggested piping uses a separate circulator
for system circulation to provide the higher flow typical of radiant
heating systems and to assure good temperature distribution in the
system when the return water temperature is low.
Circulator zoning — The GWC internal circulators must not be re-
moved. Provide a separate circulator for each zone.
Balancing, when required
valve for one of the isolation valves in each zone to use
the memory-stop valve for balancing flow as well as
isolation.
Zoning with zone valves
transformer to power the zone valves. Size the transformer
to handle the total rated load of all connected zone valves.
Alternatively, use a zone valve zone controller.
Do not use R & C connections for zone valve.
Zoning with circulators
circulator cannot be removed from the boiler for use as
one of the zone circulators. It must remain as shipped
from the factory to allow proper flow control inside the
boiler. You will need a circulator for each zone. Provide
circulator relays or circulator zone controller.
tem circulator must be supplied by the installer.
Outdoor reset
Apply Figure 23 or Figure 24 for any system intended for outdoor reset
of the supply water temperature. Use a motor-operated three-way valve
and an outdoor reset temperature control system.
1 Isolation valves
2 Automatic air vent (with diaphragm-type expansion tank), or
connect to tank fitting (closed-type expansion tank).
3 Diaphragm- or bladder-type expansion tank, if used (For closed-
type expansion tank, pipe from top of air separator to tank fitting
as in Figure 15, page 14.)
4 Zone valve
5 System or zone circulator
6 Flow/check valve
7 Hose bibb purge valve
8 Boiler pressure/temperature gauge
9 System supply temperature gauge
10 Supply temperature automatic mixing valve
11 Differential pressure by-pass valve
16 Cold water fill line — see Figure 15, page 14 for typical components
20
-
fired water boiler
(continued)
—
Substitute a memory-stop
Provide a separate 24-volt
—
— The GWC internal system
Legend
— Boiler Manual
Figure 23
Auto system supply temp regulation —
zone valve zoning
Figure 24
Auto system supply temp regulation —
The sys-
circulator zoning
MINIMUM
Boiler loop pipe size
GWC-070/105 1"
GWC-140/175 1¼"
MINIMUM
Boiler loop pipe size
GWC-070/105 1"
GWC-140/175 1¼"
Part number 550-142-786/0712